Sensor For Detection Research Articles

A Zn-MOF-based mixed matrix membrane as an ultrastable luminescent sensor for selective and visual detection of antibiotics and pesticides in food samples

The detection of antibiotics and pesticides are of great significance since their residues threaten the health of human beings by accumulation. However, most traditional solid chemical sensors are suffer from the limitations of low sensitivity and economic practicability because of the aggregating nature and unstable of solid sensors. Herein, a new luminescent sensor 1@ PMMA (1, {(ZnL)·nH2O}n (H2L, 5-(4-(pyridin-4-yl)benzamido)benzene-1,3-dioic acid); PMMA, poly(methyl methacrylate)) was successfully prepared. Notably, the polymer matrix provided the chemical protection for MOF particles. The as fabricated 1@PMMA was stable in milk, honey and egg as well as exhibited strong blue emission under ultraviolet light irradiation, which can act as luminescent probe for detecting antibiotics and pesticides. More interestingly, 1@PMMA exhibited visual, real-time and recyclable detection of antibiotics ornidazole (ODZ) and pesticides 2,6-dichloro-4-nitrobenzenamine (DCN) in real food samples. This work shows that the luminescent MOF-based mixed matrix membranes could be applied as good candidates for sensing analytes in practical application.

A Novel Molecularly Imprinted Polymer-Based Carbon Nanotube-Coated Microwave Sensor for Selective Detection of Methanol Gas

A Novel Molecularly Imprinted Polymer-Based Carbon Nanotube-Coated Microwave Sensor for Selective Detection of Methanol Gas

Molecularly Imprinted Copolymer-Based Electrochemical Sensor for Sensitive and Selective Detection of Paracetamol

Molecularly Imprinted Copolymer-Based Electrochemical Sensor for Sensitive and Selective Detection of Paracetamol

High-performance NO2 gas sensor enabled by Fe, N co-doped GQDs modification and pulse-driven temperature modulation

Nitrogen dioxide (NO2) is a typical reactive nitrogen species harmful to health and the environment. However, NO2 sensors still suffer from low sensitivity and poor response/recovery rates. Herein, 3D In2O3 assembled by stacked nanosheets were prepared and modified with N element-doped GQDs (N-GQDs) and Fe, N co-doped GQDs (Fe,N-GQDs), respectively. The results of NO2-sensing performance indicated that the optimal sample (0.3wt% Fe,N-GQDs/In2O3) showed a high response of 414.5 to 1 ppm NO2 and could detect as low as 10 ppb at 50℃, which was 1.3 and 4.0 times higher than that of 0.3wt% N-GQDs/In2O3 and In2O3, respectively. The gas-sensing kinetics were analyzed by establishing gas adsorption/desorption isotherms. The enhanced NO2 sensing properties of 0.3wt% Fe,N-GQDs/In2O3 were mainly due to the enhanced active site accessibility of stacked nanosheets with open layer spaces, the heterointerface between Fe,N-GQDs and In2O3, and electrical modulation of Fe,N-GQDs. Additionally, A pulse-driving circuit was designed for a pulse temperature modulation (PTM) strategy to further boost NO2 detection. The sensor response is further enhanced by 1.7 times, and the response/recovery time is reduced by 42.5%/60.1%. The NO2 concentration in vehicle exhaust was determined using PTM mode with good spike recoveries. It validated the reliability of the sensor for the quantitative detection of NO2 in the real environment. This work provides insights into sensor design and has the potential to contribute to the development of novel sensing platforms for other gas pollutants.

Heterostructure engineering of In2O3/ErVO4 hairy curd for high-performance TEA gas sensors

Triethylamine (TEA) is a mephitic volatile organic compound, which has huge damage to human body. Therefore, the development of gas sensitive materials for the effective detection of TEA has important application value. In this paper, In2O3, ErVO4 and In2O3/ErVO4 composite samples were successfully synthesized by hydrothermal method. The In2O3/ErVO4 composite of In2O3 and ErVO4 has a spherical structure with a rough surface, and forms a variety of porous structures, which effectively increases the specific surface area of the composite (58.9551m2/g), thereby improving the gas sensitivity to TEA. In2O3/ErVO4 composites can achieve a higher response to 100 ppm TEA (S = 54.73), have a lower optimal operating temperature (250 °C) compared with In2O3 pure samples, and have a faster recovery time (52 s) compared with ErVO4 pure samples. In addition, In2O3/ErVO4 sensors also achieve good selectivity, excellent moisture resistance, long-term stability. The microstructure of the sample was significantly changed by ErVO4 recombination. These alterations include an increase in specific surface area, a decrease in particle size, an increase in the utilization of the sensitive body, an increase in the proportion of vacancy oxygen, a decrease in the optical band gap, and an increase in electron transport efficiency. These results show that the combination of ErVO4 and In2O3 to construct heterojunction can achieve excellent sensor for TEA gas detection.

Electrochemical detection of hydroquinone as an environmental contaminant using Ga2O3 incorporated ZnO nanomaterial

The primary objective of this research endeavor is to develop a highly sensitive and selective electrochemical sensor for the accurate detection of hydroquinone (HQ), a prevalent environmental contaminant. To achieve this, we employed a novel nanocomposite consisting of Ga2O3-doped ZnO (Ga2O3.ZnO) as the active nanomaterial for fabricating a glassy carbon electrode (GCE). The structure and morphology of the Ga2O3.ZnO nanocomposite were rigorously analyzed using a diverse range of techniques to ensure its suitability as the sensing nanomaterial. This innovative sensor exhibits remarkable capabilities, enabling the detection of HQ across a broad concentration range, spanning from 1 to 11070 µM, in a neutral phosphate buffer solution. It boasts an exceptionally high sensitivity of 1.0229 µA µM−1 cm−2 and an impressive detection limit of 0.063 µM. Thanks to its exceptional sensitivity and specificity, this sensor can precisely quantify HQ levels in real-world samples. Moreover, its outstanding reproducibility, repeatability, and stability establish it as a dependable and resilient choice for HQ determination.

Smart Capsule for Targeted Detection of Inflammation Levels Inside the GI Tract.

Effective management of Inflammatory Bowel Disease (IBD) is contingent upon frequent monitoring of inflammation levels at targeted locations within the gastrointestinal (GI) tract. This is crucial for assessing disease progression and detecting potential relapses. To address this need, a novel single-use capsule technology has been devised that enables region-specific inflammation measurement, thereby facilitating repeatable monitoring within the GI tract. The capsule integrates a pH-responsive coating for location-specific activation, a chemiluminescent paper-based myeloperoxidase (MPO) sensor for inflammation detection, and a miniaturized photodetector, complemented by embedded electronics for real-time wireless data transmission. Demonstrating linear sensitivity within the physiological MPO concentration range, the sensor is capable of effectively identifying inflammation risk in the GI fluid. Luminescence emitted by the sensor, proportional to MPO concentration, is converted into an electrical signal by the photodetector, generating a quantifiable energy output with a sensitivity of 6.14 µJ/U.ml-1. The capsule was also tested with GI fluids collected from pig models simulating various inflammation states. Despite the physiological complexities, the capsule consistently activated in the intended region and accurately detected MPO levels with less than a 5% variation between readings in GI fluid and a PBS solution. This study heralds a significant step towards minimally invasive, in situ GI inflammation monitoring, potentially revolutionizing personalized IBD management and patient-specific therapeutic strategies.

Ultrasensitive DNA Origami Plasmon Sensor for Accurate Detection in Circulating Tumor DNAs

Ultrasensitive DNA Origami Plasmon Sensor for Accurate Detection in Circulating Tumor DNAs

Ultra-highly sensitive dual gases detection based on photoacoustic spectroscopy by exploiting a long-wave, high-power, wide-tunable, single-longitudinal-mode solid-state laser.

Photoacoustic spectroscopy (PAS) as a highly sensitive and selective trace gas detection technique has extremely broad application in many fields. However, the laser sources currently used in PAS limit the sensing performance. Compared to diode laser and quantum cascade laser, the solid-state laser has the merits of high optical power, excellent beam quality, and wide tuning range. Here we present a long-wave, high-power, wide-tunable, single-longitudinal-mode solid-state laser used as light source in a PAS sensor for trace gas detection. The self-built solid-state laser had an emission wavelength of ~2 μm with Tm:YAP crystal as the gain material, with an excellent wavelength and optical power stability as well as a high beam quality. The wide wavelength tuning range of 9.44 nm covers the absorption spectra of water and ammonia, with a maximum optical power of ~130 mW, allowing dual gas detection with a single laser source. The solid-state laser was used as light source in three different photoacoustic detection techniques: standard PAS with microphone, and external- and intra-cavity quartz-enhanced photoacoustic spectroscopy (QEPAS), proving that solid-state laser is an attractive excitation source in photoacoustic spectroscopy.

Efficient nanostructured Cs2CuBr2Cl2 perovskite as a fluorescent sensor for the selective “Switch Off” detection of nitrobenzene

Lead halide nanostructured perovskites are well known for their excellent photoluminescence and optoelectronic properties. However, lead toxicity and instability in moisture impedes its suitability for material use. Here we synthesized a highly efficient, lead free, economical, stable Cs2CuBr2Cl2 perovskite nanocrystals (PNCs) via Ligand Assisted Re-Precipitation (LARP) method which is less explored. The sensing application of the synthesized PNCs towards nitro explosives and other small organic compounds were studied. The probe exhibited high selectivity towards nitrobenzene with a lowest detection limit of 57.64 nM. The fluorescent emission intensity was drastically quenched upon the addition of 32 µM nitrobenzene. A Stern-Volmer plot was utilized for the quantification of fluorescence quenching. Further to investigate the quenching mechanism, time correlated single photon counting spectroscopy and other photoluminescence studies were performed pointing out the possibility of fluorescence resonance energy transfer. The work has been further extended to test the capability of the probe to detect nitrobenzene in real water samples and a good recovery percentage ranging from 93-98 % was obtained. Further, a paper strip assay was designed which successfully detected nitrobenzene and can be clearly noticed even with our naked eye making the probe an excellent sensor for nitrobenzene detection.

Emerging trends in functional molecularly imprinted polymers for electrochemical detection of biomarkers

Molecularly imprinted polymers (MIPs), functioning as artificial bioreceptors, hold significant promise for biomarker detection in healthcare, disease diagnosis, and addressing drug abuse. In contrast to natural bioreceptors, MIP-based sensors offer numerous advantages, such as high stability, cost-effectiveness, high selectivity, sensitivity, and notably straightforward preparation with customizable binding sites for diverse targets. Conventional MIP sensors often necessitate external redox reagents in analytes to transduce binding events into electrochemical signals for indirect detection, presenting challenges for practical applications in wearables or point-of-care (POC) testing. Redox-active MIP sensors have emerged as a viable alternative, enabling direct and label-free electrochemical detection, with two types developed. The first type utilizes electrocatalytic materials to expedite electron transfer and facilitate a redox reaction between the captured electroactive target and the electrode. The second type incorporates an embedded redox reactive component that allows selective binding of a target to modulate its electron transfer, leading to a change in the electrical signal. This review covers emerging trends and challenges in redox-active MIP sensors for direct electrochemical detection of biomarkers, focusing on sensing mechanisms, synthesis methods, and applications. Additionally, recent progress in wearable and POC redox-active MIP sensors is highlighted. A comprehensive outlook of challenges is further provided, aiming to advance direct biomarker detection for diverse healthcare applications.

Two swords combination: Smartphone-assisted ratiometric fluorescent and paper sensors for dual-mode detection of glyphosate in edible malt

The long-term and excessive use of glyphosate (GLY) in diverse matrices has caused serious hazard to the human and environment. However, the ultrasensitive detection of GLY still remains challenging. In this study, the smartphone-assisted dual-signal mode ratiometric fluorescent and paper sensors based on the red-emissive gold nanoclusters (R-AuNCs) and blue-emissive carbon dots (B-CDs) were ingeniously designed accurate and sensitive detection of GLY. Upon the presence of GLY, it would quench the fluorescence of B-CDs through dynamic quenching effect, and strengthen the fluorescence response of R-AuNCs due to aggregation-induced enhancement effect. Through calculating the GLY-induced fluorescence intensity ratio of B-CDs to R-AuNCs by using a fluorescence spectrophotometer, low to 0.218 μg/mL of GLY could be detected in lab in a wide concentration range of 0.3–12 μg/mL with high recovery of 94.7–103.1% in the spiked malt samples. The smartphone-assisted ratiometric fluorescent sensor achieved in the 96-well plate could monitor 0–11 μg/mL of GLY with satisfactory recovery of 94.1–107.0% in real edible malt matrices for high-throughput analysis. In addition, a portable smartphone-assisted ratiometric paper sensor established through directly depositing the combined B-CDs/R-AuNCs probes on the test strip could realize on-site measurement of 2–8 μg/mL of GLY with good linear relationship. This study provides new insights into developing the dual-signal ratiometric sensing platforms for the in-lab sensitive detection, high-throughput analysis, and on-site portable measurement of more trace contaminants in foods, clinical and environmental samples.

CsPbBr3 PQDs in EuAPO-5 Zeolite: Highly Stable Fluorescent-Traffic-Light Sensor for Point-of-Care Response of Tetracycline and Temperature

Fluorescent point-of-care (POC) sensors with specific target recognition capability through signaling mechanisms have promising applications in areas such as environmental monitoring and food detection. Herein, a solvent-free method was developed to prepare a novel POC sensor based on dual-luminescent CsPbBr3@EuAPO-5 composite that enabled the multiple sensing of tetracycline (TC) and temperature in a unique fluorescent-traffic-light manner. Benefiting from the confinement effect of EuAPO-5 zeolite, the CsPbBr3 perovskite quantum dots (PQDs) exhibits extraordinary luminescent stability even soaking in water for 30 days. During TC detection, the effective absorbed energy transfer from TC to Eu3+ in EuAPO-5 zeolite through the antenna effect enhances the red emission of Eu3+, and meanwhile a internal filtering effect (IFE) between the TC molecule and CsPbBr3 PQDs results in the green emission quenching of CsPbBr3. Combining the colorimetric determination using a smartphone-based analysis application (APP), the CsPbBr3@EuAPO-5 can serve as a portable POC sensor for TC monitoring in aqueous solution with a low detection limit of 0.013µM in a linear range of 0-140µM. Besides, ratiometric temperature sensing behavior of CsPbBr3@EuAPO-5 for high temperature warning in a fluorescent-traffic-light manner was also achieved, boosting a high sensitivity of 27.63% K-1 (at 383K) and a temperature resolution greater than 0.0035K in 293-383K. This work provides a novel bifunctional CsPbBr3 PQDs based sensor for reliable and visual detection of TC concentration and temperature, laying the foundation for the development of high-quality POC sensors with exceptional sensitivity and practicality.

Substrate integrated waveguide-based self-triplexing antenna-sensor

In this paper, a Substrate Integrated Waveguide (SIW) based self-triplexing antenna-sensor is introduced. The proposed structure can act as a sensor for concurrent detection of three chemical materials. Further, it can be used as a self-triplexing antenna for simultaneous operation at three different frequencies. To that end, initially, a half mode circular SIW cavity is designed. Then, it is divided into three parts. In each part, the position of maximum electric field is determined and subsequently, three holes are located in the positions for material insertion. Finally, considering the vacuum as the inserted material for each hole, each cavity is adjusted to operate at its operation frequency (4.8, 5.8, and 6.6 GHz). Altering the permittivity of the objects inserted in the holes, the resonant frequencies are changed and consequently the type of material is determined. The simulated and measured results validated the performance of proposed antenna-sensor as well. In all the frequency bands, the reflection coefficients as well as mutual coupling among ports are below −20 dB. It should also be expressed that such an SIW structure with the capability of sensing and propagation is provided for the first time.

Dual-responsive solvatochromic sensor for simultaneous detection and mechanism of Cr(III) and Co(II) cations by a new N2O4-donor tetrabenzodiaza-crown ether Macrocyclic ligand anchored to dipyridine moieties

The present study describes the chemosensing capability of an N2O4-donor tetrabenzodiaza-crown ether macrocyclic ligand derivatized by two pyridine side arms to afford the flexible macrocyclic ligand, 5,20-bis(pyridin-4-ylmethyl)-5,6,12,13,19,20,26,27octahydrotetrabenzo [e,i,o,s][1,4,11,14]tetraoxa[7,18]diazacycloicosine (PMHBOA). A selective colorimetric behavior of PMHBOA for the prompt detection of Cr(ΙΙΙ) and Co(ΙΙ) can be observed with naked eyes. The 1H, 13C{H} NMR, and infrared spectroscopy disclosed the ligand binding capability for selective metal ions, ascribed to a 1:1 complex formation with Cr(III) and Co(II) cations in isopropanol. The limit of detection (LOD) values were calculated as 580 and 850 nM for Cr(ΙΙΙ) and Co(ΙΙ), respectively, accompanied with suitable LOQs as 1.95 µM for Cr(III) and 2.85 µM for Co(II), respectively. The reusability was confirmed in the presence of ethylenediaminetetraacetic acid (EDTA). Moreover, a TLC-based fabricated paper strip successfully applied PMHBOA as a chemosensor for synchronous visible detection of Cr(III) and Co(II) in their alcoholic solution. Meanwhile, the observed color change along with the turn-off fluorescent of PMHBOA guaranteed a felicitous choice of candidate for Cr(III) in the presence of other library metal ions in isopropanol:H2O (9/1 v/v) solution. A fast separation test on the filter paper, impregnated with PMHBOA, was also employed to separate Cr(III) and Co(II) cations from aqueous solutions by recording UV–vis spectra. The 1H NMR spectroscopy supported the macrocycle ring and side arms as the parallel coordination site of PMHBOA with Cr(III) and Co(II).

β-Cyclodextrin/spiropyran-functionalized optical-driven hydrogel film for bisphenol a detection in food packaging

Bisphenol A (BPA), an endocrine disruptor, is widely used in food packaging materials, including drink containers. Sensitive detection of BPA is crucial to food safety. Herein, we have developed a novel optical-driven hydrogel film sensor for sensitive BPA detection based on the displacement of spiropyran (SP) from β-cyclodextrin (β-CD) cavity by BPA followed by the photochromism of the released SP. The released SP converts to the ring-opened merocyanine form which shows an enhanced red fluorescence in the dark. The sensor demonstrates a linear detection range from 0.1 to 20 μg mL−1 with a limit of detection at 0.027 μg mL−1 and a limit of quantification at 0.089 μg mL−1. Notably, the proposed β-CD/SP hydrogel can be reused due to the reversible isomerization of SP and the reversible host–guest interaction. This sensor also shows good performance for BPA determination in real samples, indicating its great potential for food safety monitoring.

Mxene-derived Na2O7Ti3 nanoribbon as a promising electrode material for the detection of ethyl paraoxon in complex matrices

This study reports the development of MXene (Ti3C2Tx) derived sodium titanate nanoribbon-based electrochemical sensor for pesticide detection. Titanium Carbide (Ti3C2) MXene-derived sodium titanate nanoribbon (MNR) was obtained by facile hydrothermal synthesis and characterized by powder X-ray Diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray analysis(EDS) and, high-resolution transmission electron microscopy (HR-TEM). The synthesized water-dispersed MNR was stabilized with Nafion and deposited on the surface of glassy carbon electrodes (GCE), which provide a symmetrical uniform electrode surface. Further, the electrodes were electrochemically characterized with cyclic voltammetry (CV), differential pulse voltammetry (DPV), linear sweep voltammetry(LSV), and electrochemical impedance spectroscopy (EIS). The electrochemical sensing of ethyl paraoxon was carried out in 0.1 M phosphate buffer (PB) by CV, LSV, and DPV. The developed electrochemical sensor exhibited a limit of detection (LOD) of 0.22 nM, a very wide detection range from 0.69 nM to 174.03 nM, and a reliable sensitivity of 0.707 µA/nM/cm2. Moreover, the developed sensor was also employed for the detection of ethyl paraoxon in real samples (vegetable extract spiked with the pesticide). The results suggest that the developed MNR-based sensor would be a potential approach for efficient and accurate detection of ethyl paraoxon in ambient samples, with minimal interference.

Electrochemical sensing of Pb2+, Cu2+, and Hg2+ by an aminoclay-based porous covalent organic polymer/ multi-walled carbon nanotubes modified glassy carbon electrode

We present a novel electrochemical sensor for the simultaneous detection of Lead (Pb2+), Copper (Cu2+), and Mercury (Hg2+) ions in seafood samples using differential pulse anodic stripping voltammetry (DPASV) technique. The sensor incorporates an aminoclay-based porous covalent organic polymer (AC-PCOP) derived from the polymerization of aminoclay and 1,3,5-benzenetricarboxylic acid (trimesic acid). To enhance conductivity, the AC-PCOP is combined with multi-walled carbon nanotubes (MWCNTs) and utilized for modifying the surface of the glassy carbon electrode (GCE). The AC-PCOP was characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, and infrared spectroscopy (IR). These analyses confirmed the presence of a hierarchical architecture in the AC-PCOP, which exhibited a spherical shape. The proposed modifier facilitates the deposition-stripping process and electron diffusion between electrolyte and heavy metal ions. Optimized conditions yielded limit of detections (LODs) of 0.0006, 0.0016, and 0.0003 nM, with linear ranges from 0.002 to 1000 nM, 0.005 to 1000 nM, and 0.001 to 1000 nM for Pb2+, Cu2+, and Hg2+, respectively. The sensor successfully measured these ions in seafood samples. Control experiments and validation were performed using cold vapor atomic absorption spectrometry (CVAAS) to determine the ions in the chosen food samples.

A reconfigurable monolith chip-type microwave gas sensor for ultrasensitive NH3 detection

A reconfigurable monolith chip-type microwave gas sensor for ultrasensitive NH3 detection

The layer-by-layer assembled ERGO+/ERGO− multilayer modified electrode for sensitive detection of dopamine

Graphene materials represented by graphene oxide (GO) have been widely regarded as functional coatings or films to modify surface of the electrode for detecting dopamine molecules. However, interfacial material properties for detection sensitivity, film stability, and applicability to electrodes are still highly desired. Herein, we first present a screen-printing carbon electrode (SPCE) coated with an electrochemically reduced layer-by-layer (LbL) assembled multilayer driven by an electrostatic interaction between positively charged polyethyleneimine-modified GO with amine groups (ERGO+) and negatively charged carboxyl-functionalized GO (ERGO−), which is briefly described as (ERGO+/ERGO−)n/SPCE. Firstly, without using conventional glassy carbon and gold electrodes, SPCE was tried to make coatings adapt to more flexible and unstable electrodes, simultaneously guaranteeing higher detection performance. Secondly, although a variety of electrochemical sensors such as GO−/SPCE and ERGO−/SPCE were obtained through the drop-casting technique, as-prepared (ERGO+/ERGO−)n/SPCE showed much higher electrocatalytic activities with enhanced peak current signals and reduced charge transfer resistance. Finally, excellent electrochemical properties and sensing performances of the (ERGO+/ERGO−)n/SPCE sensor for detection of dopamine were demonstrated, especially having a linear range of 1 μM to 1000 μM. Meanwhile, the detection limit is as low as 0.39 μM and S/N is equal to 3. The present work offers a potential direction to develop GO modified electrodes for sensitive biomolecular detection.